Furnace only stays lit for about 3 sec ,replaced flame sensor, and have checked all grounding. While testing my thermostat connections. I found that everything works fine with my volt meter touching the c terminal and ground does anybody know what the problem could be

I have the same problem with my Goodman GMV95 gas furnace. It will not stay on for more than 3 seconds. I noticed that the induced draft blower changes speed and makes a sound that I did not hear last year. Sounds like water is in it. I suspect it does not turn fast enough to pull a vacuum for one of the pressure switches. Need to investigate fuurther.

Yup! The controller board was displaying 3 flashes. The installation manual trouble shooting pointed to pressures associated with the induced draft blower. After checking some things I found the water tube coming from the blower discharge was blocked. Cleaned it and the furnace now works fine. Very simple problem and simple fix. Saved a service call... time for a beer!